If $f = x^2$,what is the relative error in $f$?

The energy of a system is given as $E(t) = \alpha^3 e^{-\beta t}$,where $t$ is the time and $\beta = 0.3 \ s^{-1}$. The errors in the measurement of $\alpha$ and $t$ are $1.2 \%$ and $1.6 \%$,respectively. At $t = 5 \ s$,the maximum percentage error in the energy is: (in $\%$)

The least count of a stopwatch is $0.2\, s$. The time for $20\, oscillations$ of a pendulum is measured to be $25\, s$. The percentage error in the measurement of time will be ........ $\%$

$A$ set of defective observation weights is used by a student to find the mass of an object using a physical balance. $A$ large number of readings will reduce:

The period of oscillation of a simple pendulum is given by $T = 2\pi \sqrt{\frac{l}{g}}$,where $l$ is about $100 \, cm$ and is known to have $1 \, mm$ accuracy. The period is about $2 \, s$. The time of $100$ oscillations is measured by a stopwatch of least count $0.1 \, s$. The percentage error in $g$ is ......... $\%$

The current-voltage relation of a diode is given by $I = (e^{1000V/T} - 1) \text{ mA}$,where the applied voltage $V$ is in volts and the temperature $T$ is in Kelvin. If a student makes an error of $\pm 0.01 \text{ V}$ while measuring the voltage to obtain a current of $5 \text{ mA}$ at $300 \text{ K}$,what will be the error in the value of current in $\text{mA}$?